Water, Freon And Public Policy

On Jan. 28, a public hearing was held by the Town of North Hempstead concerning a bond issue for improvements and additions to facilities of the Roslyn Water District.

A large audience turned out and a number of people commented on one item in the proposal, the Freon stripper for the water from a (slightly) contaminated well. The sentiments expressed ranged from apprehension to indignation.

The apprehension was mostly about the possible danger of releasing Freon into the atmosphere.

What I found distressing was the tone and manner in which the representatives of the Roslyn Water District present were treated, as if they were enemies of the people. A few observations are in order.

• The District did not put Freon R22 (“R22”) into the water source.

• The Board, managers and workers of the District do not benefit personally in any manner from the bond issue and the works to be conducted.

• Far from rushing the request for a bond surreptitiously, the District had presented the whole story in its quarterly newsletter and announced a public hearing, which was held on Jan. 9 at 7 p.m., with very low attendance.

• As reported in the newsletter, the level of R22 did not reach at any moment the threshold given as safe in the EPA rules (5 ppm). When it was found that one well contained 4.8 ppm (number reported at the hearing), the District took it out of service to be extra prudent. To ensure that water purity stays within legal limits if the R22 level continues to creep up, construction of an air stripper is part of the bond issue.

The stripper is a column through which the water circulates, while air is bubbled through it, desorbing most of R22. The air is then released at the top of the tower, containing R22 in a concentration of one hundredth of the EPA permissible level. Most of the speakers objected to the procedure, and requested that the contaminant be captured and contained, rather than released into the atmosphere. The concern that people, especially children might develop cancer from exposure to R22 vapors, which would concentrate in the lower areas, was forcefully expressed.

The only alternative to air stripping, however, is adsorption on activated charcoal, which the District engineers told us was considered but is very expensive. I have to add that the capture is not permanent; the adsorbate is just emitted, hopefully in another neighborhood, upon reactivation of the adsorbent.

There is no practical way to destroy Freon chemically. Diffusion into the upper atmosphere and photolysis, with the corresponding decomposition of the ozone layer, slowly removes them from the environment.

• The consensus was that the project should be postponed until the source of the contaminant is established and removed. This appears a sensible idea. We have to keep in mind, however, that testing is neither quick nor cheap. Enough samples have to be taken from a large enough area to determine whether there is a concentration gradient and then one pinpoints a source. The sampling might have to be conducted both at the surface and in depth.

It is possible though, that the origin of contamination is not current. First, the freons are released at ground level or above; it takes time for them to reach an aquifer at a depth of some 300 feet. That R22 is the only contaminant may even suggest an older source. Cooling technology is not my field, but 25 years ago I consulted at DuPont on synthesis of polyfluoroalkanes. The impetus was the replacement of all or most chlorine-containing cooling agents, to protect the ozone layer. I would guess that at this time R22 would be used in the U.S. mainly in mixtures; then, for a recent contamination, other compounds should also show up in water. Soil testing closer to the surface should be helpful. There is a non-zero risk, however, that the contaminant level in the wells would grow to 5 ppm before testing is completed and we are reduced to drinking bottled water.

• The danger of cancer can be addressed by the planners only within the existing laws and regulations. The documents known as MSDS, issued for all chemicals produced or used, show for all freons that no carcinogenicity has been determined. The physicians in the community might add more precise information, but my knowledge is that polyfluoroalkanes and ethers, with or without chlorine, are used as inhalation anesthetics.

This does not mean that we should not mind toxicity of these materials, especially if they have a long lifetime. All chemicals have adverse biological effects if taken in high enough doses and for long enough times. Identifying the source of contamination is easy. Air conditioning being as widespread as it is, routine malfunctions and errors add up. Among the large sources are hospitals, supermarkets and their refrigerated trucks. Historically, we have traded dying of dysentery at twelve for dying of cancer at sixty. As another source of contamination, air conditioning fluids are released in most car crashes.

In principle, we could return to ammonia as cooling agent (no ozone depletion, but the risks in case of error are serious), or to carbon dioxide. That decision would not be taken at local level and would not solve the problem of the water purity in Roslyn. For that purpose, we should build the stripper, the sooner the better.

• It was not clear to me whether the stripper is designed for the entire water supply or only for the most contaminated well. In the latter case, strippers at all other wells might be needed if the contamination will continue to increase. That might require a larger bond issue than the total sought at this time and a higher water construction for the community. (The numbers given by the District indicate that with the current bond the mid-range payment for water will increase by roughly 30 percent.) A more rational method of billing for water usage should help in using water responsibly, but that is a matter to be addressed separately.